A technique called the “MS/MS analysis (tandem analysis)” is known as a mass spectrometric technique used for a qualitative and/or quantitative determination of a known kind of component contained in a sample. For example, the MS/MS analysis is performed using a mass spectrometer (such as a tandem quadrupole mass spectrometer) having a front mass separator section for selecting a precursor ion, a fragmenting section, such as a collision cell, for fragmenting the precursor ion into product ions, and a rear mass separator section for selecting a product ion.
A multiple reaction monitoring (MRM) measurement is one of the measurement methods in the MS/MS analysis. In an MRM measurement, the mass-to-charge ratio at which an ion is allowed to pass through is fixed in each of the front and rear mass separator sections to measure the intensity of a specific product ion generated from a specific precursor ion. This combination of the precursor ion and the product ion is called the “MRM transition”. In the MRM measurement, the front and rear mass separator sections remove ions originating from components which are not the target of the measurement, ions originating from foreign components, as well as neutral particles which have not been ionized. Therefore, ion intensity signals with a high signal-to-noise (SN) ratio can be obtained even in a simultaneous analysis of a sample containing a plurality of target components or an analysis of a sample containing a considerable amount of foreign components.
Due to such merits, the MRM measurement has been used for an analysis of a sample which contains a plurality of known kinds of target components, as in the testing of agricultural chemicals contained in food samples or the testing of drugs contained in biological metabolites. For such a simultaneous analysis of multiple components, a chromatograph mass spectrometer including a chromatograph (gas chromatograph or liquid chromatograph) combined with a mass spectrometer having the previously described configuration is used. The plurality of target components contained in a sample are temporally separated by a column in the chromatograph and introduced into the mass spectrometer, to be individually subjected to the MRM measurement.
To perform an MRM measurement by a chromatograph mass spectrometer, one or more MRM measurement conditions should be previously determined for each of the plurality of target components. MRM measurement conditions include the MRM measurement time segment during which the measurement should be performed, and the MRM transition to be used in the measurement. Each MRM measurement time segment is determined so that it includes the retention time of the target component to be subjected to the measurement. The MRM transition is determined, for example, by referring to a database.
One or more MRM measurements performed for one target component are handled as one set called the “event”. The individual MRM measurements are called “channels”.